Preparation method of shuttle spokes

ABSTRACT

A preparation method of shuttle spokes that includes these steps: providing a forging die comprising of an upper die and a lower die with the upper die and lower die having a joint angle of the shuttle spoke structure and an arch radius as well as a gap between the upper die and the lower die; inserting the blank of a round spoke into the gap between the upper die and lower die for stamping; using a plurality of nip molding rollers to eliminate the burr at both ends of the shuttle spoke structure; and applying a plurality of straightening rollers to straightness adjustment of the curved spoke body so that when the wheel parts are rolling, less air vortex can minimize air resistance.

BACKGROUND OF INVENTION 1. Field of the Present Invention

The present invention relates generally to a preparation method of spokes, particularly a preparation method of shuttle shape spokes.

2. Description of Related Art

There are three types of air resistance produced by spokes, including the resistance produced by airflow hitting spokes, friction resistance, namely the friction produced by air flowing over the surface of spokes which, considering the highest speed of bicycles, almost can be ignored and exterior resistance. Generally speaking, when a wheel set is rolling at high speed, the exterior resistance is the major source of air resistance to the spokes. Flatter streamline spokes have lower wind resistance and riders can achieve a relatively high speed with fewer efforts.

The round spokes have a streamline shape, which is presently the major method to reduce the exterior resistance of spokes. There are two types of low wind-resistance spokes in the market, namely flat spokes and arch spokes and the processing methods for the spokes are forging and stamping.

Generally, the flat spokes comprise of upper and lower flat stamping dies with a part of certain thickness in between while the arch spokes comprise of upper die and lower die with arch slots and a part of certain thickness in between. Although flat spokes have simple lines, great resilience and good straightness, lacking a streamline shape, the flat spokes are less effective in reducing wind resistance compared to arch spokes. In contrast, arch spokes have lower wind resistance compared to the flat spokes as well as a streamline shape. Yet, there are restrictions of thickness. In other words, during the forging and stamping process, the upper die and lower die are likely to be damaged due to collision. Considering the restrictions of thickness, the finished products have limited streamline levels.

SUMMARY OF THE INVENTION

Considering said problems, the present invention mainly aims to: overcome the deficiencies of flat and arch spokes with regard to their appearances and preparation processes with the shuttle shape spoke structure and therefore reduce the exterior resistance of spokes.

To achieve said purpose, the present invention provides a preparation method of shuttle shape spokes that includes these steps: providing a forging die comprising of an upper die and a lower die with the upper die and lower die having a joint angle of the shuttle shape spoke structure and an arch radius as well as a gap between the upper die and the lower die; inserting the blank of a round spoke into the gap between the upper die and lower die for stamping; using a plurality of nip molding rollers to eliminate the burr at both ends of the shuttle shape spoke structure; and applying a plurality of straightening rollers to straightness adjustment of the curved spoke body.

According to an embodiment of the present invention, the shuttle shape spoke structure comprises of a spoke body and a head end and a screw thread respectively at the end of the spoke body, the head end having a neck and an expansion flat part attached to the neck with arch surfaces at the corresponding radius on the upper and lower surfaces of the section, the ends of the section including a plurality of tangent lines having the same cross point to form the joint angle and jointly comprise the shuttle shape spoke structure.

According to an embodiment of the present invention, a plurality of nip molding rollers are used to eliminate the burr at both ends of the shuttle shape spoke structure after these set of nip molding rollers at a certain angle are used for elimination of burr and formation of coning angle.

According to an embodiment of the present invention, the burr at both ends of the shuttle shape spoke structure is eliminated and a coning angle is formed with the coning angle not exceeding 90°.

According to an embodiment of the present invention, a plurality of straightening rollers are adopted to adjust the straightness of the curved spoke body after these set of straightening rollers at a certain angle are prepared for the shuttle shape spoke structure to pass through.

According to an embodiment of the present invention, a plurality of straightening rollers are adopted to adjust the straightness of the curved spoke body after the curved shuttle shape spoke structure after shuttle shape molding is put into straightening.

According to an embodiment of the present invention, the angels of the straightening rollers should not exceed 90°.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart of the preparation method of shuttle shape spokes.

FIG. 2 is a sectional view of the shuttle shape spoke.

FIG. 3 is the lateral sectional view of part of the present invention when using forging die.

FIG. 4 is the lateral view of the present invention before processing with forging die.

FIG. 5 is the front view of the present invention before processing with forging die.

FIG. 6 is the lateral view of the present invention after processing with forging die.

FIG. 7 is the front view of the present invention after processing with forging die.

FIG. 8 is the vertical view of the present invention when using nip molding rollers and straightening rollers.

FIG. 9 is a lateral sectional view of shuttle shape spoke with burr at both ends.

FIG. 10 is the lateral sectional view of the finished shuttle shape spoke.

FIG. 11 is the lateral view of part of the present invention when using straightening rollers.

FIG. 12 is the lateral sectional view of the finished shuttle shape spoke (1).

FIG. 12 is the lateral sectional view of the finished shuttle shape spoke (2).

FIG. 14 is the lateral view of the entire shuttle shape spoke.

FIG. 15 is the vertical view of the entire shuttle shape spoke.

FIG. 16 is the lateral view of another embodiment of shuttle shape spokes of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

With the following description of embodiment of the present invention, skilled technicians can easily learn other strengths and functions of the present invention through the disclosed information provided in the instruction.

Referring to FIG. 1, a flow chart of the preparation method of shuttle shape spokes, it indicates the preparation method of the shuttle shape spokes described in the present invention, including the steps as follows:

Step 901: Provide a forging die 2 comprising of an upper die 21 and a lower die 22 with the upper die 21 and lower die 22 having a joint angle θ and an arch radius 123 of the shuttle shape spoke 1 structure as well as a gap d between the upper die 21 and the lower die 22;

Step 902: Insert the blank 3 of a round spoke into the gap between the upper die 21 and lower die 22 for stamping;

Step 903: Use a plurality of nip molding rollers 4 to eliminate the burr 15 at both ends of the shuttle shape spoke 1 structure; and

Step 904: Apply a plurality of straightening rollers 5 to straightness adjustment of the curved spoke body 11.

Particularly, a plurality of nip molding rollers 4 are used to eliminate the burr 15 at both ends of the shuttle shape spoke 1 structure after these set of nip molding rollers 4 at a certain angle are used for elimination of burr 15 and formation of coning angle. In addition, a plurality of straightening rollers 5 are adopted to adjust the straightness of the curved spoke body 11 after the curved shuttle shape spoke structure after shuttle shape molding is put into straightening.

Referring to FIGS. 14 and 15, FIG. 14 is the lateral view of the entire shuttle shape spoke and FIG. 15 is the vertical view of the entire shuttle shape spoke. The present invention provides a shuttle shape spoke 1 structure, comprising of a spoke body 11 and a head end 12 and a screw thread 13 respectively at the end of the spoke body 11. The head end 12 has a neck 121 and an expansion flat part 122 attached to the neck 121 with arch surfaces 123 at the corresponding radius on the upper and lower surfaces of the section of which the ends include a plurality of tangent lines 124 having the same cross point and the two tangent lines 124 form a joint angle θ and jointly comprise the shuttle shape spoke 1 structure that is generally a rhombus.

Referring to FIG. 2, FIG. 2 is a sectional view of the shuttle shape spoke. In this embodiment, before design of the shuttle shape spoke 1, the overall width W of the section of the shuttle shape spoke should be determined to match with the wheel hub bore diameter of the selected bicycle. Second, wind resistance should be taken into consideration to determine the radius R of the streamline appearance (arch). The known width W and radius Rare applied to the determination of cross point a by drawing the tangent line ab and tangent line ac and the joint angle θ is the ∠bac (within 90°).

Referring to FIGS. 3 to 7, FIG. 3 is the lateral sectional view of part of the present invention when using forging die, FIG. 4 is the lateral view of the present invention before processing with forging die, FIG. 5 is the front view of the present invention before processing with forging die, FIG. 6 is the lateral view of the present invention after processing with forging die and FIG. 7 is the front view of the present invention after processing with forging die. The required forging die 2 is designed based on the W, R and 0 values, during which process, a gap d between the upper die 21 and the lower die 22 of the forging die 2 is reserved and the gap d maintains a certain width to prevent the dies in trial and production from collision to damage.

Referring to FIGS. 3 to 7 and FIG. 9, FIG. 9 is a lateral sectional view of shuttle shape spoke with burr at both ends. With the forging die 2, use the forging die 2 for stamping of the round spoke blank 3 to produce the semi-finished product of shuttle shape spoke 1 with burr 15, namely the shuttle shape spoke 1 with prominent burr 15 at both ends formed during elimination the section of the flat part 122.

Referring to FIGS. 3 to 7, FIG. 8 and FIG. 10, FIG. 8 is the vertical view of the present invention when using nip molding rollers and straightening rollers and FIG. 10 is the lateral sectional view of the finished shuttle shape spoke. The semi-finished shuttle shape spoke 1 with burr 15 passes through the nip molding rollers 4 at an angle (same as the joint angle θ) so that the burr 15 is removed and the coning angle (same as the joint angle θ) is formed by nipping both ends of the semi-finished shuttle shape spoke 1 with the nip molding rollers 4. As shown in FIG. 9, before processing, there is burr 15 at both ends of the shuttle shape spoke 1. As shown in FIG. 10, after processing, the burr 15 at both ends of the shuttle shape spoke 1 is removed and a coning angle is formed, which should not exceed 90°.

Referring to FIGS. 8 to 10 and 11, FIG. 11 is the lateral view of part of the present invention when using straightening rollers. Yet, during shuttle shape molding of the spoke, the spoke body 11 will be bent into a curved shape by the remaining stress. Therefore, when the shuttle shape molding of the spoke finishes, a straightening process is required. Similarly, to straighten the spoke, it should pass through a set of straightening rollers 5 at certain angles (same as the joint angle θ) within 90°. Both ends of the shuttle shape spoke 1 is pressed by a straightening roller 5 respectively to produce the shuttle shape spoke 1 of good straightness and low wind resistance.

Referring to FIGS. 4, 5 and 12, FIG. 12 is the lateral sectional view of the finished shuttle shape spoke (1). In the example, the shuttle shape spoke 1 is prepared by using a round spoke blank 3 at the diameter of 1.8 mm and the sectional area of 2.544 mm². The forging die 2 is used for stamping of the shuttle shape spoke 1. The designed width is 2.3 mm, the designed radius R is 0.9 mm, the thickness is 1.2 mm and the sectional area is approximately 2.5 mm². Upon calculation, the joint angle should reach approximately 60°.

Referring to FIGS. 4, 5 and 13, FIG. 13 is the lateral sectional view of the finished shuttle shape spoke (2). In the example, the shuttle shape spoke 1 is prepared by using a round spoke blank 3 at the diameter of 1.5 mm and the sectional area of 1.766 mm². The forging die 2 is used for stamping of the shuttle shape spoke 1. The designed width is 2.0 mm, the designed radius R is 1.0 mm, the thickness is 1.2 mm and the sectional area is approximately 1.7 mm². Upon calculation, the joint angle should reach approximately 90°.

The shuttle shape spoke structure comprises of a head end and a screw thread respectively at the ends of the spoke body. The head end has a neck at the bottom; the neck has a flat part at the bottom and the section of the flat part is shaped into a shuttle shape by processing. Therefore, when the wheel parts are rolling, less air vortex can facilitate reduction of air resistance.

Referring to FIG. 16. FIG. 16 is the schematic diagram of another embodiment of shuttle shape spokes 1 when using the section of a nose cone. In the entire range of wind conditions, the nose cone similar to flying machine has been proved to be the most effective aerodynamic design. Taking the nose cones of aircraft and flying missiles for example, when the airfoil spokes are milled to the calculated aerodynamic curve according to the same formula for calculation of the chine cone of aircraft. The comparatively blunt front edge of the spokes in the air flow reduces the rapids while the slope of the tangent lines 124 is also calculated to reduce the rapids against the rear edge to minimize the resistance.

The cross-section area ensures sufficient materials of spokes to gain the maximum strength-weight ratio.

Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the present invention as hereinafter claimed. 

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 8. Preparation method of a shuttle shape spoke includes the following steps: providing a forging die comprising of an upper die and a lower die having an arch center and meet at a parting gap that passes through center of a forging material for forming a shuttle shape structure; inserting a blank of a round spoke into the arch center between the upper die and lower die and stamping the blank spoke into a curved shuttle shape spoke structure; removing the curved shuttle shape spoke structure from the forging die and using a plurality of nip molding rollers to eliminate the burr on both sides of the curved shuttle shape spoke structure and to shape the both sides into a cone angle; and inserting the curved shuttle shape spoke structure into a plurality of angled straightening rollers to adjust the straightness of the curved shuttle shape spoke structure.
 9. The preparation method of a shuttle shape spoke as claimed in claim 8, wherein the shuttle shape spoke structure comprises of a spoke body and a head end and a screw thread disposed respectively at front and back end of the shuttle shape spoke structure; the head end having a neck and a flat part expanding from the neck; said flat part having a cross-section comprising a corresponding upper and a lower arch surface; two ends of the flat part comprising a plurality of tangent lines having the same cross point to form a joint angle and jointly forms the shuttle shape spoke structure.
 10. The preparation method of a shuttle shape spoke as claimed in claim 8, wherein, the cone angle is equal to or less than 90 degree.
 11. The preparation method of a shuttle shape spoke as claimed in claim 8, wherein, the plurality of straightening rollers are angled at equal to or less than 90 degree for allowing the curved shuttle shape spoke structure to pass through.
 12. The preparation method of a shuttle shape spoke as claimed in claim 8, wherein the straightening rollers are angled at equal to or less than 90 degree. 